Carbon nanotubes (CNTs) are carbon allotropes consisting of carbon found in abundance all over the world. CNTs are formed in such a manner that one carbon element is bonded to other carbon elements while making a hexagonal honeycomb-pattern in a tube-shape. The diameter of a CNT is in the order of a few nanometers. Recently, CNTs have been proposed as a basic element for the next generation of nanoelectronic, mechanical and nanomedical systems due to their nanoscale dimensions and outstanding materials properties, such as ballistic electronic conduction, immunity from electromigration effects at high current densities, and transparent conduction. However as commonly synthesized, CNTs vary in their diameter and chiral angle, and these physical variations may result in changes in their electronic and/or optical behavior.